1. Field of the Invention
The present invention relates to a semiconductor large scale integrated (LSI) circuit with a noise cut circuit.
2. Description of the Related Art
Recently, developments in LSI circuit techniques have enabled many LSI circuits to be put to practical use. There are, however, many problems in this practical use of LSI's, and one of these problems is to provide countermeasures against noise. Although there are many factors in the occurrence of noise, one of the main causes is switching of the circuit. For example, when output buffer circuits connected in parallel in the LSI circuit are sequentially switched, a large rush current flows from the output terminal to a power source line or a ground line. Since this rush current is a temporary flow on the line, the potential of the power source line or the ground line fluctuates so that the level of an input terminal of the LSI circuit also fluctuates. This fluctuation of the input level results in noise, and thus errors in the operation of the LSI circuit.
As countermeasures to noise, noise elimination or noise suppression techniques have been disclosed. These techniques, however, can not provide sufficient noise countermeasures for a CMOS (complementary MOS) LSI and TTL (transistor-transistor-logic) LSI.